Neuroaxonal dystrophy in the autonomic ganglia of aged rats.

Distinctive axonal abnormalities in selected sympathetic ganglia of male and female Sprague-Dawley and male Fischer 344 rats have been characterized as a function of increasing age. Dilated intraganglionic axons contained a variety of unusual subcellular organelles, including large numbers of compact or loosely aggregated tubulovesicular profiles, layered membranous loops, and collections of normal and degenerating organelles, identical to those described in clinical and experimental neuroaxonal dystrophy. Although occasional dystrophic axons were encountered free within the ganglionic neuropil, the majority were intimately associated with the surface of major dendrites or perikarya of principal sympathetic neurons and presumably represent terminal preganglionic axons. However, neither synaptic vesicles in dystrophic axons nor the association of dystrophic axons with post-synaptic densities were demonstrated. Dystrophic axons were infrequent within the prevertebral superior mesenteric and celiac ganglia before one year of age, but increased substantially in numbers thereafter. Similar findings expressed as lesions per mm2 were approximately tenfold less frequent in the paravertebral superior cervical ganglia of the same animals.